Fire damper frames

Abstract

The disclosure relates to one piece frames for fire dampers and the like. The frames are formed from elongate sheet metal blanks each of which is folded into a centrally open, generally rectangular form. In one embodiment, ends of the blank are secured together by a central tab on one end which extends through a T-shaped slot formed at the opposite end of the blank. In another embodiment, the blank is secured in its folded form by an angle shaped end bracket and the frame is provided with at least one corner bracket forming a gusset. The blanks have inwardly directed flanges which are formed with V-shaped notches to permit folding of the blank. In one embodiment, the notches each define an angle of less than 90° and portions of the flange on each side of the notch are overlapped when the blank is folded to provide for frictional engagement between the overlapped portions. In another embodiment, the notches each define an angle of 90° so that the edges of the flange at opposite sides of the notch come into abutting relationship when the blank is folded.

I claim: 
     
       1. A one piece frame for fire dampers and the like, the frame being of centrally open, generally rectangular shape formed from a folded elongated sheet metal blank which, in its unfolded form, comprises: (a) a longitudinally extending central web portion of planar form   (b) side edge portions which are longitudinally bent so as to define: (i) a pair of longitudinally extending marginal regions of double blank thickness for permitting mounting of the frame in an air duct or the like and;   (ii) a pair of longitudinally extending parallel flanges disposed inwardly of said marginal regions and extending perpendicular to and disposed at the same side of the planar web portion, said flanges being divided into sections by V-shaped notches which extend over the entire height of the flange and which are intended to define corners of the completed frame, each section being aligned with sections of the other flange transversely of the blank and extending along a side of the completed frame;     (c) a first end portion including two tabs which extend beyond an outer edge of said web portion and which are shaped to define therebetween an open T-shaped slot having a stem portion and a transverse portion, said transverse portion defining part of said outer edge;   (d) a second end portion including a central tab shaped to fit through and fold over the transverse portion of the T-shaped slot when the frame is in its folded form and adapted to be folded over to retain the frame in said form, and outer tabs adapted to be folded over said outer edge of the web when the frame is in its folded form; said blank being folded transversely at the positions of said notches with the flanges extending inwardly in forming the frame.     
     
     
       2. A frame as claimed in claim 1, wherein said V-shaped notches define an enclosed angle of 90° and are symmetrical about a line normal to said planar web portion whereby portions of said flanges on opposite sides of said slots are disposed in abutting relationship when the blank is in its folded form. 
     
     
       3. A frame as claimed in claim 1, wherein said V-shaped notches define enclosed angle of less than 90° and portions of said flange sections adjacent each notch are laterally distorted with respect to the remainder of said sections in folding said blank so as to cause said portions to overlap and provide for frictional engagement of said portions when the frame is in its folded form. 
     
     
       4. A frame as claimed in claim 1, wherein said marginal regions of double blank thickness and said flanges terminate short of said tabs at the second end portion of the blank, and wherein the blank is formed by die cutting sheet metal stock to a predetermined shape and roll forming the resulting work piece to form said folded elongated sheet metal blank. 
     
     
       5. A frame as claimed in claim 1, wherein each of said outer tabs is at least partly of double blank thickness and is formed by a continuation of the relevant one of said marginal regions of the blank, and wherein the blank is formed by roll forming sheet metal stock into random lengths each having said marginal regions of double blank thickness and flanges, and die cutting sand random lengths into sections of predetermined length while simultaneously forming said first and second end portions and said V-shaped notches. 
     
     
       6. A one piece frame for fire dampers and the like, the frame being of centrally open, generally rectangular shape, and comprising: (1) a folded elongate sheet metal blank which, in its unfolded form, comprises: (a) a longitudinally extending central web portion of planar form   (b) side edge portions which are longitudinally bent so as to define: (i) a pair of longitudinally extending marginal regions of double blank thickness for permitting mounting of the frame in an air duct or the like and;   (ii) a pair of longitudinally extending parallel flanges disposed inwardly of said marginal regions and extending perpendicular to and disposed at the same side of the planar web, said flanges being divided into sections by V-shaped notches which extend over the entire height of the flange and which are intended to define corners of the completed frame, each section being aligned with the sections of the other flange transversely of the blank and extending along a side of the completed frame;     (c) end portions having straight edges perpendicular to said parallel flanges; the blank being folded transversely at the positions of said notches with the flanges extending inwardly and said end portions in abutting relationship;     (2) an end bracket of angle shape in cross-section joining said abutting end portions of the blank, said bracket being disposed externally on said end portions, and said bracket and said blank including aligned holes receiving fastening means firmly securing said bracket to the blank, and;   (3) at least one corner bracket including a gusset of right triangular shape and two flanges which project laterally from edges of the gusset adjacent its right angle at the same side of said gusset and normally thereto, said corner bracket being disposed internally of the frame at a corner thereof remote from said bracket with said flanges overlying portions of one of said marginal regions of the blank at the relevant corner of the frame, said portions and flanges including aligned holes receiving fastening means firmly securing the corner bracket to the blank.   
     
     
       7. A claim as claimed in claim 6, wherein said V-shaped notches define an enclosed angle of 90° and are symmetrical about a line normal to said planar web portion whereby portions of said flanges on opposite sides of said slot are disposed in abutting relationship when the blank is in its folded form. 
     
     
       8. A frame as claimed in claim 6, wherein said V-shaped notches define an enclosed angle of less than 90° and portions of said flange sections adjacent each notch are laterally distorted with respect to the remainder of said sections in folding said blank so as to cause said portions to overlap and provide for frictional engagement of said portions when the frame is in its folded form.